That means, including active team names, there have been 55 different team names in NHL history (or 56 if you consider the two distinct Ottawa Senators and Winnipeg Jets franchises as different).

Note: this does not include every team that has won the Stanley Cup. The NHL did not come into existence until the 1917-1918 season, but there were Stanley Cup winners from 1892-1917. That list is for another node.